In general, a mobile electronic device is powered from a rechargeable battery to improve the portability thereof. Examples of the mobile electronic device may include various types of acoustic, image and information devices, such as a mobile communication device (a so-called mobile phone), a digital camera, a digital multimedia player (DMP), a portable multimedia player (PMP), an MP3 player (MP3P) and a personal digital assistant (PDA). In addition, the demands of users are also significantly increasing.
A mobile communication device, presented as an example of the mobile electronic device, uses an external rechargeable battery and an internal rechargeable battery. The external rechargeable battery is detachably mounted to the backside of a mobile communication device body so as to be seen from outside, whereas the internal rechargeable battery received in the backside of the mobile communication device body is enclosed from outside by a cover.
Recently, in mobile communication devices, accidents caused by the explosion of rechargeable batteries are frequently occurring. An accident involving a rechargeable battery is more dangerous than other accidents since it can directly lead to explosion or fire. Thus, safety regulations related to rechargeable batteries are being further intensified in many countries.
A rechargeable battery such as a lithium (Li) ion rechargeable cell is apt to explode or cause fire when it is exposed to heat. To prevent this, safety regulations require that the charging of the rechargeable battery be interrupted when the rechargeable battery is heated to a predetermined temperature or higher.
Conventionally, a temperature measuring device called a thermistor is generally used to control the operation of a mobile communication device by detecting the temperature thereof. The thermistor is a device whose resistance varies as a function of temperature. The resistance varying with temperature causes a voltage variation, which a processor can detect to recognize a temperature change.
While the temperature of the rechargeable battery can be correctly measured using the thermistor mounted inside the battery, contact terminals for transmitting signals to the processor are additionally provided in the rechargeable battery, thereby increasing manufacturing costs.
Furthermore, while the thermistor can be fitted in a circuit board through a simple process, heat from the circuit board makes it difficult to correctly measure the temperature of the thermistor.